Thermally responsive switch devices



Sept. 10, 1963 .1. LIEBERMANN ET AL 3,103,568

THERMALLY RESPONSIVE SWITCH DEVICES 6 Sheets-Sheet 1 Filed May 1961INVENTORS JOHN LIEBERMANN THOMAS [.SYFERT CLYDE K.STORER JAMES M.CROWLEY BY 7 g A RNEY Sept. 10, 1963 J. LIEBERMANN ETAL 3,103,563

THERMALLY RESPONSIVE SWITCH DEVICES I BY 1:- g s v A ORNEY Sept. 10,1963 J. LIEBERMANN ETAL 3,103,558

THERMALLY RESPONSIVE SWITCH DEVICES Filed May 5, 1961 s Sheets-Sheet alle J ORNEY Sept. 10, 1963 J. LIEBERMANN ETAL THERMALLY RESPONSIVESWITCH DEVICES Filed May 5. 1961 6 Sheets-Sheet 4 CLYDE K.STORER JAMESM. CROWLEY BY 7 f %NEY Sept. 10, 1963 J. LIEBERMANN ETAL 3,103,568

THERMALLY RESPONSIVE SWITCH DEVICES Filed May 5, 1961 6 Sheets-Sheet 5 l"J 4 i g [I I [74/ ///j L FIG. 6

FIG. 7 INVENTORS JOHN LIEBERMANN THOMAS l. SYFERT CLYDE K. STORER JAMESM.CROWLEY Sept. 10, 1963 .1. LIEBERMANN ETAI. 3,103,568

THERMALLY RESPONSIVE SWITCH DEVICES 6 Sheets-Sheet 6 Filed May 5, 1961wdE ll Ill/A INVENTORS JOHN LIEBERMANN THOMAS l. SYFERT A ORNEY Ohio, acorporation of Ohio Filed May 5, 1961, Ser. No. 107,951 ,5 Claims. cl.zoo-nae i I This invention relates to thermally actuated electric switchdevices and more specifically to a novel and 1mproved constructionin'that type of switch devicewl'l-ich.

embodies a snap acting switch mechanism, a thermally responsive powerelement for operation thereof, and adjustable means for varying theoperating characteristics of the switch device.

Electric switch devices of the type with which the invention isconcerned are particularly suited for use in the thermostatic control ofrefrigerators, air-conditioners and the like apparatus, wherein anelectric compressor motor is cyclically operated in response totemperature variations in the apparatus or in the medium being heated orcooled. The temperature variations to which the switch devices mustrespond "differ with each apparatus and often with each application ofthe same type of apparatus. Moreover, ''with the trend toward less bulkyappliances and apparatus being accomplished by better insulation methodsand materials as well as miniaturization of parts, the space which maybe occupied by a switch device is at a premium. Accordingly, it isdesirable ,to provide such switch devices which are compact in size andwherein the operating characteristics, such as the cut-in or closingoperation and the cut-out or opening'oper-ation can be independentlyadjusted or set to vary the spread or differential therebetweemandwherein these characterist-ics can be simultaneously adjustedor set by-manual control means without substantial change in the dilrerential, soasto permit selection of a desired temperature level United StatesPatent 3,103,568 Patented SepLiIO, 1963 effect of range spring onthebellows engaging lever whereby the temperature responsivecharacteristics of the switch may :be selectively changed.

Still another object of this, invention is the provision of the togglemember and the bellows engaging lever in theform of bell cranks arrangedso as to define a space therebetween for accommodating the adjustinglever and range spring, the bell cranks being pivoted aboutparallel axesand arranged with one leg of each extending toward but terminating shortof one leg of the other bell crank with the over-center spring meansdisposed therebetween, and the other leg of each bell crank extendingsubstantially parallel to and in the same direction as that of the otherbell crank so as to define the mentioned space between the parallel legsthereof.

Another object of the present invention is the provision of improvedswitch means embodying theforegoing constru'ctions and in one form ofwhich the cut-out and cut-in temperature characteristics may besimultaneously varied by a single control, and in another form of whichone of those temperature characteristics is maintained constant althoughthe other is varied.

As another object the invention aims to provide other constructions andarrangements of parts, the objects and advantages of which will becomeapparent from the following description of the preferred embodiments ofthe to .be maintained by a refrigerator, air conditioner, or

the like under the control of the switch device; v,

As one object, this invention aims to provide an improved thermallyresponsive switch device of the above mentioned character in whichcertainnovel constructions andarrangements of parts providetheaforementioned desirable features, the device comprising a generallyrectangular housing formed at least in part by an insulator memberlocated at one end thereof and which carries a movable switch contactand a fixed contact, the movable contact being actuated for cooperationwith the fixed contact by a toggle member in the form 'of a lever armpivoted to the insulator memberfand extending alongside thereof andbeing connected with the movable" device having the above describedarrangement of parts and wherein the snap acting mechanism may beconveniently and accurately adjusted to select the-temperaturesinvention and from the accompanying sheets of drawings forming a part ofthis sepcification, and in which:

FIG. 1 is a perspective view of a thermally responsive switch deviceembodying this invention; FIG. 2 is another perspective view of thedevice of FIG. 1; a a FIG. 3 is a section-a1 'view of the switch devicetaken substantially along line 33 of FIG. 1 and on an enlarged scale;

FIG. 4 is a view similar to FIG. 3 but with some parts in differentpositions;

PIG. 5 is a sectional viewtaken substantially along FIG. 1;

FIG. 7 is a sectional view taken along line 7-7 of F iG.3;and

FIG. 8 is a sectional view similar to FIG. 3 but illustrat-;

ing a modified switch device embodying this invention,

Inthe form of the invention illustrated and described in FIGS. 1 through7, there is provided a thermally actuated electric switch device,generally indicated at 10,

which is particularly useful in controlling the cyclic operation ofrefrigerant compressors in refrigerators, air condi tioners and thelike, in responseto temperature fluctuations. The switch device 10includes a housing comprising I a channel shaped member 1:1,preferablyformed of sheet metal, and comprisingsidewalls 11a, 11b joined bya wall110. An insulator member 12, formed of molded Bakelite or other suitableinsulating plastic material extends from between the walls 11a, 11b ofchannel member 11 so as to form one end portion of the housing.insulator member 12 comprises an end wall 12a, side walls 12b and 120,and a bottomwall 12d, and is conveniently secured in place by lugs 122extending through at which the switch contacts will be operated betweenopen I and closed positions, the mechanism including, a bellows engaginglever pivoted in thehousing for movementabout one axis and connected byover-center spring means to the toggle member for effecting the snapaction thereof,

and an adjusting lever pivoted to one housing wall for movement about anaxis transverse to the axis of the bellows engaging lever, the adjustinglever being connected by a range spring'to the bellows engaging leverand being adjustably positioned by cam means for varying the biasingcorresponding openings in the, walls of channel member 11.A'ternperature responsive snap switch mechanism,

described hereinafter, is located within the housing formed by channelmember 11 and insulator member 12. The; housing is preferably closed onthe side opposite wall by an insulating cover member 14 which is adaptedto;-

slide between walls 11a and 11b andto be held by the inturned edgeportions of those walls as is best shown in FIG. 2. A mounting bracket15, having apertured ears I or lugs 15a, overlies wall 11b and issecured thereto by tabs 11d as shown.

AYcb iuc'mr member 16 extends through, and is secured in, an'opening inend wall12a of insulator member 12 andterniinatesat its outer end in ablade type terminal connector 16a. -A flexible con-tact arm 17',isformed of fiatspring metalsuch'as beryllium copper and has an inturnedend l7a secur'ed tothe inner end of conductor 15 by welding or thelike'..-Contact arm 17 carries a movand 20 when open. A washer 36'0fnylon or other suitable materialsurrounds screw 34 and serves to lockthat screw in its adjusted position.

able cntactf18 located at the mid'portion thereof, as I shown.All-shaped second conductor member 19, havping arelativelyfixed contact20 supported on the inner, or yoke portiong 19a thereof, is mounted oninsulator member '12 with contact 20 in registration with movablecontact 18. *Conductor member 19 has two leg portions extending through,and secured in, openings in insulator 1 wall 12a-and terminatinginfblade type terminal connectors 19b and 19c Snap actingactuator meansareprovided for operating contact arm 17 to bring contact 20 into andout of en-" gagement with contact 18 for making and breaking an elec- Il tric' circuit therethrough. In this instance the snap acting mechanismcomprises a toggle member 22, which is pivoted to insulator member 12,and a bellows operated lever 2s which will later bedescribed'indetaihhte toggle member and the lever being opera Lively interconnectedby a C-s'haped over-center acting toggle spring 24;

One leg 22a of togglemember 22 is molded from- Bakelite? or "othersuitable rigid insulating material,

while another leg thereof comprises a metal plate 221; riveted to onevend of leg 22a at right angles thereto so that toggle member '22 takesthe form of bell crank lever. Plate 22b is provided with knife edges '25engaged in v shap'ed notches 26; formed in insulator member =12 "to-efiiect the pivotal'connection of -toggle member 22 therewith, and isprovided with knife edge 27 engaging one-end 2421 of toggle spring 24. I1

Leg 22a extends across insulator member 12 and termi-v nates inanoffse't portion 220 which projects between Rotation of lever 23 in :acounter-clockwise direction about the pivotal axis f defined by fulcrumpin 29 will move or bring the pivotal connection between spring end 245and knife edge3 3 through a plane extending through fulcrum pin 29 andthe pivotal connection of toggle member 22 with insulator member 12.*Upon such passing of knife edge 33 through that plane, spring 24 willact against plate 22b of toggle member 22 causing the latter to rotatein a counter-clockwise direction into the position shown in FIG. 4 witha snap acting movement. As

the insulator'side .walls' 12b and 120 and has an opening 22d in whichthe tree end portion 17c of contact arm 17 I is loosely'caged. 'Tlhus,movement of toggle member 22 in a clockwise" direction as viowed 'inFIG. 3 will cause I I the offset portion 220 to-move the caged end 170of arm 17 and to separate con-tact 2th from contact 18 against theresilient spring action of arm'l7, while counter-clock- I wisemovementiofftoggle member 22 will permit spring Y ar'm17-to close thecontactsas shown in FIG. 4.

Lever 23,;which is preferably formed as a sheet metal of a bell crank,and is pivotally connected to channel member 11 by'a triangular'tfulc'rum pin 29 which extends between sidewalls 11a and 11b and passesthrough openings 30 in spaced. bearing member 230 extending from leg 23bLegf23b and togglemember leg 22 1 ex- I tend substantially parallel tqone "another. and in the same direction, while-the plate-22b and leg 23aextend toward, but terminate shorto'f, one another. A generallyrectangular space is therebydefined between the toggle member 22and-bellows lever 23,'which space is utilized to accommodatelother parts1 ently be made apparent.-

of the device, as will pres- Bellows leverleg 23a is provided withaknife edge 38 which is pivotally connected with end 24b of toggle spring24(I When lever23 is in its position illustrated in FIG. 3,

. spring 24 acts against plate 22b of toggle member 22, .urgingthelatter in a oloclowise'direction, as viewed in IIth'e'draWingsQ-abQut the pivotal axis formed by knife edge 25 andgrooves 26 so that-offset portion 220 holds 9 contact arm 17 withmovable contact'ltl separatedfrom ,fixed'contactN. Movementof togglemember 22in this -dir e ction is limited by engagement of 'olfsetportion 22c with a screw 34 which extends through a threadedopenstamping, comprises leg portions23a and 23b extending.

substantially at right anglesto one another in the manner I will serveto change the amount of movement of lever 23 necessary to snap theswitch means toits closed position.

'Dhenmally responsive power means are provided for moving lever 23 aboutits pivot'pin' 29 for actuation of the switch mechanism and. in thisi'nstance comprises an expansible bellows, generally indicated at 44 andhaving an axially extending post tti a in engagement with an adjust-ingscrew 41 received in a threaded opening 23d in leg 23b of lever 23.Bellows 40 forms part of an assembly comprising aniend plate 44 to whichthe bellows is secured as bybrazing and whichisin turn secured to sidewalls 11a, l-lb by tabs llle crimped thereover. A"

tubular member 46 extends: from end plate 44 and communicatestherethrough with the interior of the bellows. Tubular member 46 isclosed and sealed at its other end, andthe bellows 40 and tubular membercontain a fluid which.=expands and contracts with increases anddecreases in temperature. Temperature changes experienced by the tubularmember 46 result in axial expansion and contraction of bellows 40 whichis transmitted via post 401; and screw41'to leg 2% of lever 23. Endplate 44, maybe conveniently provided with tongues 44b which serve togrip cover 14.

A tension spring 48 is disposed in the previously mentioned spacebetween toggle member 22 and lever 23fand 1 is connected at one end4811' thereof to a hook 4?, which is struck out from leg 23a of lever23', and this spring serves to resiliently unge lever '23 in a clockwisedirection about pivot pin 29 and against the post 40a of bellows,threadedly engaged in a nut member 51 lodged in the I eonvolutions ofspring 48, to an adjusting lever 52, in a i 40. Spring 48 is connectedat its other end by ascrew 50,

recessed opening of which screw head so: is received.

Lever'52 'has spaced bearing portions 52aiextending thro'ugh slots 53 inhousing side wall 11b and serving to pivotal-1y. connect the leverthereto for rotation about an axis extending transverselyof the offulcrum pin 29.

Lever 52 is also provided with a cam following portion 52b extendingtherefrom and adapted to engage the periphe'ry of a rotatable cam '55.

ing a lug 35 struckinwardly fromhousing Wall. 11a, and acts as anadjustable stop for toggle member 22,

thereby determining the spacing between contacts 1-8 Cam 55 is connectedto a shaft 56 for rotation therewith, the, shaft being suitablyjournaled in an opening in wall 11b and being adapted to receive a knob,notshown,

for conveniently adjusting the position of cam 55, Rotation of cam 55serves, toadjustably position 1ever 52 for increasing or decreasing thetension of spring 48, and hence for-adjusting the load imposed onbellows 40. By this means,'which simultaneously f shifts the cut in andcut out temperatures without substantially altering the spread ordifferential therebetween, the temperatures at which the snap actingswitch mechanismwill be actuated may be conveniently selected. ScrewStlmay also be adjusted to vary the tension on spring 48 and serves toshift the range of temperatures which'may be selected by use of the cam55. Screw 50 may therefore be referred to as a range adjusting screw andspring 48 as a range spring. H

In some applications, in domestic refrigerators for example, it isdesirable to provide an off position for the temperature control knob.Switch, therefore ineludes means whereby the contacts 18 and 20 may bemaintained in an open condition regardless of increases in temperature.Forthis purpose cooperable hook members 58and 59 are provided on leverarms 23a and 52 respectively. When shaft 56 is rotated in a manner tobring the highest portion 55a of cm 55 to bear against cam follower 52bof lever 52, the latter is moved so as to bring hook member 59 intoengagement with hook member 58. Lever 23 is thereby restrained againstmovement by bellows 40 and contacts 18 and 20 will be held openregardless of temperature changes experienced by the tubular element 46.7

Referring now to FIG. 8, in which parts corresponding to those alreadydescribed have corresponding reference characters, there is illustratedtherein a modified switch device which may be referred to as a constantcut-in and variable cut-out device. That is to say, rotation of controlshaft 56 serves only to adjust the temperature at which the contacts 18and 20 open. This is accomplished by keeping the tension on range spring48 constant and varying the amount of movement of bellows 40 necessaryto actuate the switch to open the contacts.

.The tension'on range spring 48 is maintained constant by providing anoff cam 55' on shaft 56 with a profile whichwill not shift cam follower52b except when the V follower is engaged by the cam rise indicated at55" so as to cause hook members 58 and 59 to hold the switch in the offposition. A out-out temperature selecting cam 65 is provided on shaft56in addition to the off Cam 65 is disposed adjacent the inner surfaceof housing wall 11b and'the periphery thereof is'engaged by a lever arm67 extending from toggle member 22 and conveniently formed as a part ofplate 22b. Arm 67 and cam 65 cooperate .to limit movement of togglemember 22 in a counter-clockwise direction and hence serve to adjustablydetermine the amount of movement of bellows 40 and lever 23 necessary tosnap'the toggle member to its switch opening position and therefore toadjustably determine the cut-out temperature of the switch device. Whilein the FIG. 3 embodiment rotation of shaft 56 and cam 55 serve tosimultaneously shift the cut-in and cut out temperatures, in the presentembodiment only the tions and arrangements of parts including a togglemem-- her and a bellows engaging lever in the form of two bell cranklevers disposed so as to provide space therebetween for-adjustableloading or biasing means, and the insulator member which forms the endportion of the housing and pivotally supports the toggle member, thecontact means and the differential adjusting means, there have beenprovided particularly compact yet simple and reliable switch devices.Moreover, it will be appreciated that switch devices embodying thisinvention are easily regulated and adjusted by means which are readilyaccessible, so that the devices lend themselves to use in a variety ofapparatus and applications.

Although the invention has been described with detailed reference toparticular switch devices,'it will be understood that the invention isnot limited thereby, but rather the invention includes'all suchadaptations, modifications,

having one constant and'one variable operating characteristic, saiddevice having housing means at least one portion of which comprises aninsulator member forming one end of the housing, said insulator memberalso supporting a relatively fixed contact in said housing forcooperation with said movable contact arm, a snap acting mechanism insaid housing including a toggle member pivoted to said insulator memberfor movement about a first axis between first and second positions foractuating said movable contact arm, a lever pivoted in said housing formovement about a second axis and connected to said toggle member by anover-center acting spring, a temperature responsive power element formoving said lever to effect snap movement of said toggle member betweensaid first and second positions, adjustable biasing means urging saidlever in one direction against said power element, said adjustablebiasing means including a second lever pivoted to a wall of said housingfor movement about an axis transverse to said second axis, spring meansconnecting said second lever and the first mentioned lever, and controlmeans including a rotary cam engaging said second lever for positioningthereof to select said variable operating characteristic, and meansconnecting said toggle member and said control means for changing one ofsaid first and second positions in accordance with positioning of saidsecond lever whereby said constant characteristic is unaffected by saidselection of said variable operating characteristic.

2. A switch device as defined in claim- 1 wherein said control meanscomprises a second cam rotatable with the first mentioned cam, and saidmeans connecting said toggle member and said control means comprises anarm extending from said to gle member and engaging said second cam. Y

3. A thermally responsive switch device of the character describedhaving housing means at least one portion of which comprises aninsulator member forming one end of the'housing, said insulator membersupporting a movable contact arm in said housing, said insualtor memberalso supporting a relatively fixed contact in said housing forcooperation with said movable contact arm, a snap acting mechanism inthe housing including a toggle member pivoted to said insulator memberfor movement about a first axis between first and second positions foractuating said movable contact arm, temperature responsive power meansin said housing at the other end thereof for operating said snap actingmechanism, said snap acting mechanism comprising a lever pivoted in saidhousing for movement about a second axis and connected to said togglemember by an over-center acting spring, said lever being movable by saidtemperature responsive power means for effecting snap movement of saidtoggle member between said first and second positions, and adjustablebiasing means including a second lever pivoted to a wall of said housingfor movement about an axis transverse to said second axis and urging thefirst mentioned lever in one direction against said power element.

4. A switch comprising first and second bell cranks mounted for movementabout first and second axes respectively, each bell crank having one legextending toward and terminating short of one leg of the other bellcrank, each bell crank having its other leg extending parallel to and inthe same direction as the other leg of the other bell crank to define aspace therebetween, first spring means between said one leg of each bellcrank for elfecting snap acting movement of said first bell crankbetween first and second positions upon predetermined rotative movementof said second bell crank, electrical contact means operable by theother leg of said first bell crank upon said snap acting movements tomake and break a circuit therethrough, second spring means acting Lonsaid one leg of said second bell crank for biasing thereof in onedirection of rotation, thermally responsive plower means acting on theother leg of said second bell erank- [for eflecting rotation "thereof insaid other direction against the action oflsaidsecondspiring means,

7 whereby said second bell crank is rotated and said contact means -.areoperated in accordance with predetermined fluctuations in temperature, acam and a lever movable by said cam, said second spring m-eans beingconnected to said lever for adjustment by rotation of said cam, said camand lever being disposed in the space between said parallel other legsof said bell cranks, and: said lever being pivoted for rotation about"an axis 'transverse to said second axis.

5. A switch as defined in claim 4 and wherein said second spring meansis adjustable whereby said contact means are operable in accordance withdifferent predetermined temperature fluctuations;

References Cited-in the file of this patent UNITED STATES PATENTS 7,Greenawalt Jan. 14, 1958--

1. A THERMALLY RESPONSIVE SWITCH DEVICE OF THE TYPE HAVING ONE CONSTANTAND ONE VARIABLE OPERATING CHARACTERISTIC, SAID DEVICE HAVING HOUSINGMEANS AT LEAST ONE PORTION OF WHICH COMPRISES AN INSULATOR MEMBERFORMING ONE END OF THE HOUSING, SAID INSULATOR MEMBER ALSO SUPPORTING ARELATIVELY FIXED CONTACT IN SAID HOUSING FOR COOPERATION WITH SAIDMOVABLE CONTACT ARM, A SNAP ACTING MECHANISM IN SAID HOUSING INCLUDING ATOGGLE MEMBER PIVOTED TO SAID INSULATOR MEMBER FOR MOVEMENT ABOUT AFIRST AXIS BETWEEN FIRST AND SECOND POSITIONS FOR ACTUATING SAID MOVABLECONTACT ARM, A LEVER PIVOTED IN SAID HOUSING FOR MOVEMENT ABOUT A SECONDAXIS AND CONNECTED TO SAID TOGGLE MEMBER BY AN OVER-CENTER ACTINGSPRING, A TEMPERATURE RESPONSIVE POWER ELEMENT FOR MOVING SAID LEVER TOEFFECT SNAP MOVEMENT OF SAID TOGGLE MEMBER BETWEEN SAID FIRST AND SECONDPOSITIONS, ADJUSTABLE BIASING MEANS URGING SAID LEVER IN ONE DIRECTIONAGAINST SAID POWER ELEMENT, SAID ADJUSTABLE BIASING MEANS INCLUDING ASECOND LEVER PIVOTED TO A WALL OF SAID HOUSING FOR MOVEMENT ABOUT ANAXIS TRANSVERSE TO SAID SECOND AXIS, SPRING MEANS CONNECTING SAID SECONDLEVER AND THE FIRST MENTIONED LEVER, AND CONTROL MEANS INCLUDING AROTARY CAM ENGAGING SAID SECOND LEVER FOR POSITIONING THEREOF TO SELECTSAID VARIABLE OPERATING CHARACTERISTIC, AND MEANS CONNECTING SAID TOGGLEMEMBER AND SAID CONTROL MEANS FOR CHANGING ONE OF SAID FIRST AND SECONDPOSITIONS IN ACCORDANCE WITH POSITIONING OF SAID SECOND LEVER WHEREBYSAID CONSTANT CHARACTERISTIC IS UNAFFECTED BY SAID SELECTION OF SAIDVARIABLE OPERATING CHARACTERISTIC.